This episode stemmed from an idea Robert Hewitt Wolfe had in which Miles O'Brien would discover that he was not the original O'Brien, but rather a Cardassian who had replaced the original at the Setlik III massacre as a deep cover agent with false memories. This would have meant that O'Brien had been a Cardassian spy during his entire time on Star Trek! Wolfe never pushed the story too hard because it never made sense to him how a Cardassian O'Brien would have been the father to Molly, a clearly 100% Human child.

As a result, the basic idea was used for Raymond Boone in the episode "Tribunal", and then here for Kira in "Second Skin".

The original plan for this episode was to have an ambiguous ending, dangling the possibility that Kira really was, and always had been, a Cardassian disguised as a Bajoran.

Nana Visitor is somewhat claustrophobic, and found this episode incredibly difficult because the Cardassian makeup felt very constricting. In her last scene she literally started ripping the makeup off her face as she ran off the set in panic.

Plotline

Kira is shocked to wake and find herself on Cardassia, with the face of a Cardassian woman. Worse still, Legate Ghemor insists that she is his daughter and that her life as a Bajoran was a ruse designed to allow her to operate as an intelligence officer. As the evidence mounts, Kira must consider the possibility that her entire life has been a lie.